* {
    box-sizing: border-box;
}
body {
    width: 100%;
    min-width: 320px;
    max-width: 640px;
    margin: 0 auto;
    font-size: 14px;
    font-family: -apple-system, Helvetica, sans-serif;
    color: #666;
    line-height: 1.5;

}
ul {
    margin: 0;
    padding: 0;
    list-style: none;
}
img {
    /* 图片默认和文字的基线对齐，因此需要修改为和文字中线对齐 */
    vertical-align: middle;
}
a {
    color: #666;
    text-decoration: none;
}
.clearfix:before,
.clearfix:after {
    content: "";
    display: table;
}
.clearfix:after {
    clear: both;
}
.clearfix {
    *zoom: 1;
}
/* 头部区域 */
.app {
    height: 45px;
}
.app ul li {
    float: left;
    height: 45px;
    background-color: #333;
    text-align: center;
    line-height: 45px;
    color: #fff; 
}
.app ul li:nth-child(1) {
    width: 8%;

}
.app ul li:nth-child(1) img {
    width: 10px;
} 
.app ul li:nth-child(2) {
    width: 10%;
}
.app ul li:nth-child(2) img {
    width: 30px;
} 
.app ul li:nth-child(3) {
    width: 57%;
}
.app ul li:nth-child(4) {
    width: 25%;
    background-color: #F63515;
}
.app ul li:nth-child(4) a {
    color: #fff;
}

/* 搜索区域 */
.search_wrap {
    position: fixed;
    top: 45px;
    width: 100%;
    height: 44px;
    min-width: 320px;
    max-width: 640px;

}
.search_btn {
    float: left;
    width: 40px;
    height: 44px;
    margin-right: 10px;
}
.search_btn::before {
    content: '';
    display: block;
    width: 20px;
    height: 18px;
    margin: 14px 0 0 15px;
    background: url(../images/s-btn.png);
    background-size: 20px 18px;
}
.search {
    position: relative;
    float: left;
    margin-top: 7px;
    width: calc(100% - 100px);
    height: 30px;
    background-color: #fff;
    border-radius: 15px;
    overflow: hidden;
}
.search .jd_icon {
    position: absolute;
    top: 8px;
    left: 13px;
    width: 20px;
    height: 15px;
    background: url(../images/jd.png) no-repeat;
    background-size: 20px 15px;
}
.search .jd_icon::after {
    content: '';
    display: block;
    width: 1px;
    height: 15px;
    background-color: #ccc;
    margin-left: 30px;
}
.search .fangdajing {
    position: absolute;
    top: 8px;
    left: 50px;
    width: 18px;
    height: 15px;
    background: url(../images/jd-sprites.png) -81px 0;
    background-size: 200px 200px;
}
.search input {
    position: absolute;
    top: 0;
    left: 70px;
    height: 100%;
    width: calc(100% - 70px);
    outline: none;
    border: 0;
}
.search_login {
    float: left;
    width: 40px;
    height: 44px;
    margin-left: 10px;
    text-align: center;
    line-height: 44px;
    color: #fff;
}

/* 主体区域 */
.slide img {
    width: 100%;
}

.brand {
    border-radius: 10px 10px 0 0;
    overflow: hidden;
}
.brand div {
    float: left;
    width: 33.33%;
}
.brand div img {
    width: 100%;
}

.mainContent nav a {
    float: left;
    width: 20%;
    text-align: center;
}
.mainContent nav a img {
    width: 40px;
    margin: 10px 0;
}
.mainContent nav a p {
    margin: 0;
}

.news {
    margin-top: 20px;
}
.news a {
    float: left;
    
}
.news a:nth-child(1) {
    width: 50%;
}
.news a:nth-child(1) img {
    width: 100%;
}

.news a:nth-child(n+2) {
    width: 25%;
    border-left: 1px solid #ccc;
}
.news a:nth-child(n+2) img {
    width: 100%;
}